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Older adults with visual impairments: the role of health dimensions in predicting falls

OLDER ADULTS WITH VISUAL IMPAIRMENTS: THE ROLE OF HEALTH
DIMENSIONS IN PREDICTING FALLS
by
Bernard Alex Steinman
________________________________________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(GERONTOLOGY)
December 2010
Copyright 2010 Bernard Alex Steinman

The purpose of this dissertation was to examine relationships between self reported vision impairment, health dimensions, and falls among older people; and to describe an indirect pathway through which vision loss may increase risk for falls by way of poor health outcomes in dimensions of health that are believed to lead to disability. Whereas previous research has tended to focus on direct effects of vision loss on fall risk, the primary goal of this research was to examine integrated effects between systems that might lead to increased fall risk via moderated or mediated relationships.; First, in order to establish health disparities by self reported vision status, binary and multinomial logistic regression models were performed using data from the National Health and Nutrition Examination Survey, 1999-2008 (N=6,693) to estimate the probability of negative health outcomes across four dimensions of health, including biological risk, pathological conditions, functional difficulties and disability in daily living activities, by vision status. Results suggest that older adults with poor vision have greater likelihood of experiencing negative health outcomes across the four dimensions.; Next, two waves (2004 & 2006) from the Health and Retirement Study (HRS) (N=8,449) were analyzed using binary logistic regression to investigate whether a moderating relationship exists between vision status and upper and lower limb functioning. This relationship was hypothesized to derive, in part, from decreased physical activity that often follows vision loss in late life, to result in poorer functional ability. Little evidence was found for a moderating effect of self-reported vision status on musculoskeletal health and functioning; however, results suggest that declines and/or gains in functioning across short periods of time may supercede self-reported vision as a predictor of falls. Thus, poor self-reported vision status may not be as good an indicator of fall risk in older adults as might otherwise be assumed.; In a third study, two waves (2006 & 2008) from HRS (N = 9,143) were used to test whether functional difficulties and disability with daily living activities mediate self-reported vision loss to increase fall risk among older adults. Binary logistic and Poisson regression analyses were conducted to test indirect paths leading from self-reported vision to falls, through declines in indices of functioning and disability. No evidence was found for a mediating effect among women; however, for men, large muscle groups were implicated as partially mediating risk factors for falls among participants with poor vision.; Finally, implications of the three studies are discussed, including the need for prioritizing improved muscle strength of older persons with vision impairments as preventive measure against falls. It is acknowledged that the most effective fall prevention interventions are likely multifactorial in structure; therefore, interventions pertaining to education, medical assessment, exercise, and home assessment and modification are discussed with respect to older persons who have vision impairments.

OLDER ADULTS WITH VISUAL IMPAIRMENTS: THE ROLE OF HEALTH
DIMENSIONS IN PREDICTING FALLS
by
Bernard Alex Steinman
________________________________________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(GERONTOLOGY)
December 2010
Copyright 2010 Bernard Alex Steinman